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diff --git a/docs/syntax/syntax.md b/docs/syntax/syntax.md new file mode 100644 index 0000000..31c7f8d --- /dev/null +++ b/docs/syntax/syntax.md @@ -0,0 +1,491 @@ +(syntax/core)= + +# Core Syntax + +## Introduction + +MyST is a strict superset of the [CommonMark syntax specification](https://spec.commonmark.org/). +It adds features focussed on scientific and technical documentation authoring, as detailed below. + +In addition, the roles and directives syntax provide inline/block-level extension points for plugins. +This is detailed further in the [Roles and Directives](roles-directives) section. + +:::{seealso} +The [syntax token reference tables](syntax-tokens) +::: + +(syntax/commonmark)= + +## CommonMark + +The [CommonMark syntax specification](https://spec.commonmark.org/) details the full set of syntax rules. +Here we provide a summary of most features: + +Element | Syntax +--------------- | ------------------------------------------- +Heading | `# H1` to `###### H6` +Bold | `**bold**` +Italic | `*italic*` +Inline Code | `` `code` `` +Autolink | `<https://www.example.com>` +URL Link | `[title](https://www.example.com)` +Image | `` +Reference Link | `[title][link]` +Link Definition | `[link]: https://www.example.com` +Thematic break | `---` +Blockquote | `> quote` +Ordered List | `1. item` +Unordered List | `- item` +Code Fence | opening ```` ```lang ```` to closing ```` ``` ```` + +(syntax/frontmatter)= + +## Front Matter + +This is a [YAML](https://en.wikipedia.org/wiki/YAML) block at the start of the document, as used for example in [jekyll](https://jekyllrb.com/docs/front-matter/). +The document should start with three or more `---` markers, and YAML is parsed until a closing `---` marker is found: + +```yaml +--- +key1: value +key2: [value1, value2] +key3: + subkey1: value +--- +``` + +:::{seealso} +Top-matter is also used for the [substitution syntax extension](syntax/substitutions), +and can be used to store information for blog posting (see [ablog's myst-parser support](https://ablog.readthedocs.io/en/latest/manual/markdown/)). +::: + +### Setting a title + +```{versionadded} 0.17.0 +``` + +If `myst_title_to_header` is set to `True`, and a `title` key is present in the front matter, +then the title will be used as the document's header (parsed as Markdown). +For example: + +```md +--- +title: My Title with *emphasis* +--- +``` + +would be equivalent to: + +```md +# My Title with *emphasis* +``` + +(syntax/html_meta)= + +### Setting HTML Metadata + +The front-matter can contain the special key `html_meta`; a dict with data to add to the generated HTML as [`<meta>` elements](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/meta). +This is equivalent to using the [RST `meta` directive](https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#html-metadata). + +HTML metadata can also be added globally in the `conf.py` *via* the `myst_html_meta` variable, in which case it will be added to all MyST documents. +For each document, the `myst_html_meta` dict will be updated by the document level front-matter `html_meta`, with the front-matter taking precedence. + +::::{tab-set} +:::{tab-item} Sphinx Configuration + +```python +language = "en" +myst_html_meta = { + "description lang=en": "metadata description", + "description lang=fr": "description des métadonnées", + "keywords": "Sphinx, MyST", + "property=og:locale": "en_US" +} +``` + +::: + +:::{tab-item} MyST Front-Matter + +```yaml +--- +myst: + html_meta: + "description lang=en": "metadata description" + "description lang=fr": "description des métadonnées" + "keywords": "Sphinx, MyST" + "property=og:locale": "en_US" +--- +``` + +::: + +:::{tab-item} RestructuredText + +```restructuredtext +.. meta:: + :description lang=en: metadata description + :description lang=fr: description des métadonnées + :keywords: Sphinx, MyST + :property=og:locale: en_US +``` + +::: + +:::{tab-item} HTML Output + +```html +<html lang="en"> + <head> + <meta content="metadata description" lang="en" name="description" xml:lang="en" /> + <meta content="description des métadonnées" lang="fr" name="description" xml:lang="fr" /> + <meta name="keywords" content="Sphinx, MyST"> + <meta content="en_US" property="og:locale" /> +``` + +::: +:::: + +(syntax/comments)= + +## Comments + +You may add comments by putting the `%` character at the beginning of a line. This will +prevent the line from being parsed into the output document. + +For example, this code: + +```md +% my comment +``` + +Is below, but it won't be parsed into the document. + +% my comment + +````{important} +Since comments are a block-level entity, they will terminate the previous block. +In practical terms, this means that the following lines +will be broken up into two paragraphs, resulting in a new line between them: + +``` +a line +% a comment +another line +``` + +a line +% a comment +another line +```` + +:::{tip} +Comments are equivalent to the RST syntax: `.. my comment`. +::: + +(syntax/blockbreaks)= + +## Block Breaks + +You may add a block break by putting `+++` at the beginning of a line. +This constuct's intended use case is for mapping to cell based document formats, +like [jupyter notebooks](https://jupyter.org/), +to indicate a new text cell. It will not show up in the rendered text, +but is stored in the internal document structure for use by developers. + +For example, this code: + +```md ++++ some text +``` + +Is below, but it won't be parsed into the document. + ++++ + +(syntax/referencing)= + +## Markdown Links and Referencing + +Markdown links are of the form: `[text](link)`. + +If you set the configuration `myst_all_links_external = True` (`False` by default), +then all links will be treated simply as "external" links. +For example, in HTML outputs, `[text](link)` will be rendered as `<a href="link">text</a>`. + +Otherwise, links will only be treated as "external" links if they are prefixed with a scheme, +configured with `myst_url_schemes` (by default, `http`, `https`, `ftp`, or `mailto`). +For example, `[example.com](https://example.com)` becomes [example.com](https://example.com). + +:::{note} +The `text` will be parsed as nested Markdown, for example `[here's some *emphasised text*](https://example.com)` will be parsed as [here's some *emphasised text*](https://example.com). +::: + +For "internal" links, myst-parser in Sphinx will attempt to resolve the reference to either a relative document path, or a cross-reference to a target (see [](syntax/targets)): + +- `[this doc](syntax.md)` will link to a rendered source document: [this doc](syntax.md) + - This is similar to `` {doc}`this doc <syntax>` ``; {doc}`this doc <syntax>`, but allows for document extensions, and parses nested Markdown text. +- `[example text](example.txt)` will link to a non-source (downloadable) file: [example text](example.txt) + - The linked document itself will be copied to the build directory. + - This is similar to `` {download}`example text <example.txt>` ``; {download}`example text <example.txt>`, but parses nested Markdown text. +- `[reference](syntax/referencing)` will link to an internal cross-reference: [reference](syntax/referencing) + - This is similar to `` {any}`reference <syntax/referencing>` ``; {any}`reference <syntax/referencing>`, but parses nested Markdown text. + - You can limit the scope of the cross-reference to specific [sphinx domains](sphinx:domain), by using the `myst_ref_domains` configuration. + For example, `myst_ref_domains = ("std", "py")` will only allow cross-references to `std` and `py` domains. + +Additionally, only if [](syntax/header-anchors) are enabled, then internal links to document headers can be used. +For example `[a header](syntax.md#markdown-links-and-referencing)` will link to a header anchor: [a header](syntax.md#markdown-links-and-referencing). + +(syntax/targets)= + +## Targets and Cross-Referencing + +Targets are used to define custom anchors that you can refer to elsewhere in your +documentation. They generally go before section titles so that you can easily refer +to them. + +:::{tip} + +If you'd like to *automatically* generate targets for each of your section headers, +check out the [](syntax/header-anchors) section of extended syntaxes. + +::: + +Target headers are defined with this syntax: + +```md +(header_target)= +``` + +They can then be referred to with the [ref inline role](https://www.sphinx-doc.org/en/master/usage/restructuredtext/roles.html#role-ref): + +```md +{ref}`header_target` +``` + +By default, the reference will use the text of the target (such as the section title), but also you can directly specify the text: + +```md +{ref}`my text <header_target>` +``` + +For example, see this ref: {ref}`syntax/targets`, and here's a ref back to the top of this page: {ref}`my text <syntax/core>`. + +Alternatively using the markdown syntax: + +```md +[my text](header_target) +``` + +is equivalent to using the [any inline role](https://www.sphinx-doc.org/en/master/usage/restructuredtext/roles.html#role-any): + +```md +{any}`my text <header_target>` +``` + +but can also accept "nested" syntax (like bold text) and will recognise document paths that include extensions (e.g. `syntax/syntax` or `syntax/syntax.md`) + +Using the same example, see this ref: [](syntax/targets), here is a reference back to the top of +this page: [my text with **nested** $\alpha$ syntax](syntax/core), and here is a reference to another page (`[](../intro.md)`): [](../intro.md). + +```{note} +If you wish to have the target's title inserted into your text, you can +leave the "text" section of the markdown link empty. For example, this +markdown: `[](syntax.md)` will result in: [](syntax.md). +``` + +(syntax/code-blocks)= +## Code syntax highlighting + +Code blocks contain a language identifier, which is used to determine the language of the code. +This language is used to determine the syntax highlighting, using an available [pygments lexer](https://pygments.org/docs/lexers/). + +````markdown +```python +from a import b +c = "string" +``` +```` + +```python +from a import b +c = "string" +``` + +You can create and register your own lexer, using the [`pygments.lexers` entry point](https://pygments.org/docs/plugins/#register-plugins), +or within a sphinx extension, with the [`app.add_lexer` method](sphinx:sphinx.application.Sphinx.add_lexer). + +Using the `myst_number_code_blocks` configuration option, you can also control whether code blocks are numbered by line. +For example, using `myst_number_code_blocks = ["typescript"]`: + +```typescript +type MyBool = true | false; + +interface User { + name: string; + id: number; +} +``` + +### Show backticks inside raw markdown blocks + +If you'd like to show backticks inside of your markdown, you can do so by nesting them +in backticks of a greater length. Markdown will treat the outer-most backticks as the +edges of the "raw" block and everything inside will show up. For example: + +``` `` `hi` `` ``` will be rendered as: `` `hi` `` + +and + +````` +```` +``` +hi +``` +```` +````` + +will be rendered as: + +```` +``` +hi +``` +```` + +## Tables + +Tables can be written using the standard [Github Flavoured Markdown syntax](https://github.github.com/gfm/#tables-extension-): + +```md +| foo | bar | +| --- | --- | +| baz | bim | +``` + +| foo | bar | +| --- | --- | +| baz | bim | + +Cells in a column can be aligned using the `:` character: + +```md +| left | center | right | +| :--- | :----: | ----: | +| a | b | c | +``` + +| left | center | right | +| :--- | :----: | ----: | +| a | b | c | + +:::{note} + +Text is aligned by assigning `text-left`, `text-center`, or `text-right` to the cell. +It is then necessary for the theme you are using to include the appropriate css styling. + +```html +<table class="colwidths-auto table"> + <thead> + <tr><th class="text-left head"><p>left</p></th></tr> + </thead> + <tbody> + <tr><td class="text-left"><p>a</p></td></tr> + </tbody> +</table> +``` + +::: + +## Images + +MyST provides a few different syntaxes for including images in your documentation. + +The standard Markdown syntax is: + +```md + +``` + + + +But you can also enable extended image syntaxes, to control attributes like width and captions. +See the [extended image syntax guide](syntax/images). + +(syntax/footnotes)= +## Footnotes + +Footnotes use the [pandoc specification](https://pandoc.org/MANUAL.html#footnotes). +Their labels **start with `^`** and can then be any alphanumeric string (no spaces), which is case-insensitive. + +- If the label is an integer, then it will always use that integer for the rendered label (i.e. they are manually numbered). +- For any other labels, they will be auto-numbered in the order which they are referenced, skipping any manually numbered labels. + +All footnote definitions are collected, and displayed at the bottom of the page (in the order they are referenced). +Note that un-referenced footnote definitions will not be displayed. + +```md +- This is a manually-numbered footnote reference.[^3] +- This is an auto-numbered footnote reference.[^myref] + +[^myref]: This is an auto-numbered footnote definition. +[^3]: This is a manually-numbered footnote definition. +``` + +- This is a manually-numbered footnote reference.[^3] +- This is an auto-numbered footnote reference.[^myref] + +[^myref]: This is an auto-numbered footnote definition. +[^3]: This is a manually-numbered footnote definition. + +Any preceding text after a footnote definitions, which is +indented by four or more spaces, will also be included in the footnote definition, and the text is rendered as MyST Markdown, e.g. + +```md +A longer footnote definition.[^mylongdef] + +[^mylongdef]: This is the _**footnote definition**_. + + That continues for all indented lines + + - even other block elements + + Plus any preceding unindented lines, +that are not separated by a blank line + +This is not part of the footnote. +``` + +A longer footnote definition.[^mylongdef] + +[^mylongdef]: This is the _**footnote definition**_. + + That continues for all indented lines + + - even other block elements + + Plus any subsequent unindented lines, +that are not separated by a blank line + +This is not part of the footnote. + +````{important} +Although footnote references can be used just fine within directives, e.g.[^myref], +it is recommended that footnote definitions are not set within directives, +unless they will only be referenced within that same directive: + +```md +[^other] + +[^other]: A definition within a directive +``` + +[^other] + +[^other]: A definition within a directive + +This is because, in the current implementation, they may not be available to reference in text above that particular directive. +```` + +By default, a transition line (with a `footnotes` class) will be placed before any footnotes. +This can be turned off by adding `myst_footnote_transition = False` to the config file. |